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Relationship Between Chromosome Knob Number and Yield in Corn 1
Author(s) -
Wellhausen E. J.,
Prywer Czeslawa
Publication year - 1954
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1954.00021962004600110008x
Subject(s) - citation , library science , political science , humanities , agricultural science , sociology , biology , philosophy , computer science
T HE presence of knobs in the chromosomes of corn (Zea ma),s) and its related genera teosinte (Euchlaena mexituna, Schrod.) and gama grass (Tripsacum sp.) has been dearly demonstrated by McClintock (5) and Longley (1) . Mangelsdorf and Reeves (3) and Mangelsdorf and Cameron (2) have demonstrated an association of knobs with certain plant characters. With these results as a basis, they formulated the hypothesis that the original corn was knobless, and that knobs in corn were derived by repeated crossing with teosinte, which in turn was derived from txevious hybridization between corn and 73"ipsarmn. More recently, Mangelsdorf and Smith (4) , in a stud), of the prehistoric corn cobs found in Bat Cave in New Mexico, present evidence which indicates that primitive corn was both tunicate and a popcorn, and that teosinte came into existence some time later and played a very important part in the subsequent evolution of corn. It is thus entirely kPossible that corn may have received at least many of its hobs from teosinte. The knobs themselves may have no genetic effect but may have associated with them segmerlts of teosinte germplasm homologous or partially homologous to segments in maize. I f Mangelsdorf and Reeves (3) are correct in their hypothesis that teosinte originated as a cross between corn and Tripsacmn, then the germplasm might well be Tripsacum germplasm. Wellhausen et al. (8) , in a study of the races of corn in Mexico, found that the most productive races of corn all show a strong introgression of teosinte. Furthermore, races which were derived from the intercrossing of two other races in general had a higher chromosome knob mualber than the average of die putative parents. In certain races of hybrid origin the knob number was higher than that of either one of the parents. This indicated that there might be some relationship between chromosome knob ntmabers and yield in corn, although Vachhani (7) found no relationship between daromosome knob numbers and the various plant characters, including yield, in a study of 20 corn inbred lines of diverse origin used in the breeding program of the Minnesota Agricultural Experiment Station. In order to obtain additional dater on the suggested relationship, the following study was designed to determine the association, if any, between chromosome knob number of an inbred line and its yield capacity in topcrosses, comparing lines within many different varieties of corn in Mexico.